quantum-espresso/examples/example08

This example shows how to calculate the Density of States (DOS) and
how to plot the Fermi Surface of Ni .

The calculation proceeds as follows (for the meaning of the cited input
variables see the appropriate INPUT_* file)

1) make a self-consistent calculation for Ni (like in example 1).
   (input=ni.scf.in, output=ni.scf.out)

2) make a band structure calculation for Ni (input=ni.dos.in,
   output=ni.dos.out) on a uniform k-point grid (automatically
   generated). In this example the Fermi level is calculated with the
   tetrahedra method (not in the actual band structure calculation but in
   the subsequent DOS calculation). If preferred, a gaussian broadening
   may be specified in this or in the subsequent step.

3) the program dos.x reads file filpun (ni.pun) and calculates the DOS on a
   uniform grid of energies from Emin to Emax, with grid step Delta E.
   The output DOS is in file ni.dos, ready for plotting.

4) the program projfwc.x projects the crystal wavefunctions on an
   orthogonalized basis set of atomic orbitals, calculates the Loewdin
   charges, spilling parameter, and the projected DOS (total DOS in file
   'ni.pdos_tot', s and d component in files 'ni.pdos_atm#1(Ni)_wfc#1(s)'
   and 'ni.pdos_atm#1(Ni)_wfc#2(d)' respectively).  (input=ni.pdos.in,
   output=ni.pdos.in)

5) Fermi Surface plot, courtesy of
      Eyvaz Isaev
      Theoretical Physics Department
      Moscow State Institute of Steel and Alloys
      (eyvaz_isaev@yahoo.com, e.isaev@misis.ru)
   First, one generates a  grid of k-points (all of them, not only those
   in the Irreducible Brilloin Zone) using auxiliary code kvecs_FS.x
   Then, the non-scf calculation is performed
   Then, auxiliary code bands_FS.x collects the data and produces a
   file ni.fs.bxsf that can be read by XCrySDen (www.xcrysden.org) as:
      xcrysden --bxsf ni.fs.bxsf 
   Additional info for customization of the script:
#
# A user has to edit so-called "user part" in order to define some required 
# parameters.
# 
# Sysname   - a nickname for your system
# Calc_Type - The Fermi Surface calculations (FS) or band-structure
#             calculations (Band) which will be included later. 
#             Presently band-structure calculations could be carried out 
#             by means of plotband.x from PP (postprocessing) directory 
#             or a little package distributed by E.Isaev (posted to pw_forum). 
# nabc      - a number for dividing of each edge of a parallelepiped.
#             Be careful, the total number of generated k-points is
#             (na+1)*(nb+1)*(nc+1), i.e. including \Gamma-point.
# n_start   - starting band's number for the Fermi Surface calculations.
#             It is obvious, we have to deal with the bands crossing the
#             Fermi level.
# n_last    - last band's number for FS calculations
#
# That's all!!! Present values in the script (may be edited):
Sysname='ni'
Calc_Type='FS'
nabc=' 16 16 16 '
n_start=2
n_last=5
#
#
# Nota Bene : You can take more bands and then choose from a XCrySDen menu
#             only those bands which cross the Fermi level   
# Nota Bene : If you have mistaken choosing bands to be considered for the
#             FS construction, you do not need to restart all calculations.
#             Just edit "bands_FS" file and restart "bands_FS.x" manually.
#             It will read Bands.out and result Bands.bxsf which you can
#             rename as you like.
#  
# Spin-polarized calculations are not allowed, but will be done soon.